1. Field of the Invention
The present invention relates to a sequence control device using a microcomputer for use in a camera system provided with automatic focusing and automatic exposure control.
2. Description of the Prior Art
It is desired that data are processed in a high speed in parallel by using two exclusive microcomputers for the calculation of an automatic exposure control and for the calculation of an automatic focus control. However, the cost of a camera having two microcomputers for controlling a camera becomes very expensive. Therefore, there have been proposed various processing ways of two above mentioned calculation using only one microcomputer.
For example, in the control system of a camera shown in Japanese Patent Laid Open No. 172628/1983, the calculation for exposure control is executed fundamentally by using interruption with a predetermined interval to a microcomputer for automatic focus control. However, in this case since the calculation for the exposure control is executed by interruption during the automatic focus control, the time period for the automatic focus control becomes long.
In the control system of a camera shown in Japanese Patent Laid Open No. 125817/1985, the time period for the automatic focus control is shortened by allowing the subsequent focus detection during the calculation processing of the data for the automatic focus control obtained by the preceding focus detection, but the exposure control is not considered.
Moreover, in the control system of a camera shown in Japanese Patent Laid Open No. 172628/1983, the time period for charge accumulation in a CCD image sensor of a focus detection device varies with the brightness of a photographic object. Additionally the driving speed of a photographic lens for automatic focus control is different depending on the defocus amount the shifting distance of the photographic lens to the in-focus position) or the torque necessary for shifting the photographic lens, the time interval control for the automatic focus control is difficult, resulting in difficulty of effective use of the microcomputer.